The Best Looking Solar Panels You’ve Never Seen

Perfect Symmetry?

If you are interested in having solar PV (electric) panels, but are discouraged by the effect the installation will have on how your home looks you are not alone. 

The headlong rush to get solar electric systems installed before cuts to the wildly popular government incentive scheme, the Feed-in-Tariff, created a focus on financial returns as the only goal.  A number of Crimes Against Architecture may have been perpetrated.  Ladies and gentlemen of the jury, its up to you.  Consider the gallery below.

Exhibit A

Have these installations knocked more off the value of the property than they will ever make in Feed in Tariff profits?  Am I being too harsh?  Let me know what you think - post a comment below.

Got any any better (worse!) photos of solar installations? Send them to me at this email address: thesolarblogger@yahoo.com and I’ll enhance the gallery. Credit given to contributors.

[UPDATE: Thanks to all who have sent photos - I have created an album on Flicker which you can see here]

An arbitrary Feed-In-Tariff banding structure has encouraged people to fit the maximum number of panels possible up to the 4kWp threshold at which the tariff reduces, sometimes with little thought for aesthetics.

Standardised solar installation kits offering a fixed number of of panel numbers further limits the chance of creating a sensitive roof layout.

The good news is that it doesn't have to be this way. There are alternatives available to those who want to reduce their energy use while protecting the appeal of their property.

It Doesn’t Have to Be This Way - The Best Solar Panels You’ve Never Seen

The default installation of solar pv is a rack-mounted checkerboard of solar panels mounted above the roof covering.  Due to their ubiquity many people think this is the only option available.

Fortunately for those who want a more harmonious-looking  installation, alternatives  do exist.  So-called integrated solar panels that replace tiles or slates in the roof covering, offering a much neater, low-profile installation.  These can be either tile-format panels where small panels fit into the tiles of the roof, or rectangular panels with a weathertight interface between panels and tiles.

Roof integrated solar panels (left) and solar tiles (right)

Some properties with smaller or awkward roof areas might be better served with a solar heating system. This requires far less roof area than it's electric counterpart, and can also be installed as a roof integrated system.  The forthcoming Renewable Heat Incentive could make this type of solar more popular, and systems installed now will qualify for the incentive once it starts as if installed on the first day of the scheme.

For more examples of roof-integrated solar panels check out the Viridian Solar Gallery.

Peak Toil - Update on UK Photovoltaic Market

Challenge to Business Studies students:


Look at the chart above and write a business plan to create a sustainable long-term business based on photovoltaic solar in the UK.  Your plan must take account of the fact that the spikes are randomly imposed by the actions of the greenest government ever, determined as it is to help the industry by continuously "improving" the Feed-in-Tariff, the grant scheme that creates the demand for your products and services.


This is an update of an earlier chart showing the effects changes to the Feed in Tariff (FIT) have had on installation rates of solar PV in the UK.


Worried that they would over-spend the Treasury budget cap for the FIT, the government announced its intention to cut the subsidy in half from December 2011.  The ensuing rush of installations to get in before the cuts was followed by a second peak at the end of March 2012, as it became clear that the government had acted unlawfully with it's first date, and the new FITs would come in from March 3rd.


A third mini-peak erupted in the run up to April 2012 as another change was made to the FITs requiring that houses should have an Energy Performance Certificate (EPC) with a rating of D or higher to qualify for the FIT.


Following the third deadline, solar PV installation rates have remained stubbornly low, despite prices for PV having fallen to a level that means the return on investment is apparently similar to that during 2011.


The current Feed in Tariff rates and requirements can be found here.

More Like a Car Than a Computer - Improvements in Solar PV Panel Efficiencies

Hard work if you can get it
How PV solar efficiency has improved over time

My phone has more computing power than it took to put a man on the moon, doesn't it?

Nowadays we take epic rates of improvement in performance and cost for electronic products in our stride.  It's a commonly held belief that the performance of PV solar panels are following a similar trajectory, but what does the reality look like?

Since 1975, the National Renewable Energy Laboratory in Colorado, USA has been plotting the current world's best efficiency for a range of different types of solar photovoltaic cells. The image above is a simplified version of a more detailed chart. I have shown only the three technologies in most common use and added two recent technical developments of great promise.

The efficiency shown here is not what you would expect to achieve from a commercially available solar pv panel, rather from a small, carefully prepared, no-expenses-spared laboratory sample.

The graph tells a story of hard-won gains over long periods of time more akin to the gradual improvements in fuel efficiency in cars than to improvements in computers, LCD televisions and digital cameras.  In the same time scale that rooms full of mainframe computers have shrunk down to fit into you pocket, the efficiency of solar panels has increased from about 14% to about 24%. 

You see, the bad news is that there's a Law's-of-Physics-type-limit to the efficiency of a solar cell and it's only 34% for the single junction technology that most solar panels use.  As you approach this limit the gains get harder and harder to win. You can see that the world record for silicon solar cell efficiency started to flatten off around 1995, polycrystalline around 1998, and that thin film cells are reaching a similar point right about now. 

 

Bright New Stars

Two exciting technology developments that have the potential to drive future improvements are organic cells and multi-junction thin film cells.

Organic cells are made from plastic photovoltaic materials, with the benefits of low cost and simple manufacturing processes that such materials bring. As can be seen in the graph, these new materials are just starting out, with low but rapidly rising efficiencies. They are quickly approaching the point where interesting applications will emerge - for example where the larger areas needed for the same power output are not a disadvantage, or the shapes that can be formed are important.

Multi-junction thin film cells sidestep the efficiency limit of conventional solar cells. Layers of photovoltaic material are stacked one on top of the other, each tuned to a different wavelength of light.  As light travels through the stack, each layer slices out the energy associated with the colour of light to which it is tuned.  The theoretical limit to efficiency for such a cell jumps to 64%.  Laboratory samples have already broken through the efficiency limit for a single layer cell.

There's good reason to be optimistic that further progress can be made in PV technology, just remember that today's laboratory record-breaking material can take many years to find its way into proven, real-world products.

Coming out of the Shade - Will the Renewable Heat Incentive Provide a Much Needed Boost for Solar Thermal in the UK?

While the Feed in Tariff has been grabbing all the headlines, the government has quietly launched a similar cash-back scheme for solar heating in commercial applications, but where are the best opportunities?

At the end of 2011 photovoltaic solar energy was hardly out of the news, with legal challenges to the government’s management of the Feed in Tariff and a dash to install before tariff levels dropped.  Among all of this, it would have been easy to miss the fact that the government has launched a similar cash-back scheme for renewable heat technologies, including solar thermal.

The Renewable Heat Incentive

This solar heating installation for an Extracare building
would qualify for the Renewable Heat Incentive

Launched in November 2011, the Renewable Heat Incentive (RHI) is aimed at all buildings with installations of solar heating with the exception of single domestic premises.  It currently pays the owner of the solar system 8.9 pence per kilowatt-hour (kWh) of heat generated, with the tariff index-linked for the duration of the scheme.  The owner can claim the cash-back every quarter for 20 years from the date of registration.


Read a more detailed briefing on the scheme here.

Eligible buildings include commercial properties or groups of houses or apartments served by a single communal solar system.  Domestic buildings are intended to come under the scheme during summer 2013, with a consultation expected this September.

Where are the Opportunities?

Any building that has a need for hot water is an opportunity for solar thermal, but some are more attractive than others.  These include:

Residential

Accommodation for students at universities, junior staff at hospitals and pupils at boarding schools often have a centralised plant room where water is heated for distribution around the building.  It can be relatively straightforward to install a solar buffer tank to pre-heat the water for the existing heating system.  Sheltered accommodation and Extracare buildings are often heated in the same way, and if residents are assisted to bathe during the working day, then a smaller solar buffer tank can be used.

Apartment blocks can pose a more difficult challenge to the integration of solar water heating, especially if each apartment has its own individual heating system.  However solar heating systems which generate heat from a communal solar array and transfer it to hot water cylinders in individual apartments via a distribution ring are possible (see case study).

Leisure

Hotels often have a high water demand, and if the occupancy of holiday accommodation is seasonally biased towards the summer months, then the effectiveness of a solar system can be higher due to supply matching demand.

Swimming pools are an excellent application for solar heating because the low demand temperature means the solar panels work at maximum efficiency.  Coupled to this, the large thermal capacity of the pool allows the full use of energy on sunny days, where storage capacity might limit the energy collection for a domestic hot water system.

Health Care

Hospitals and surgeries can have a high demand for hot water and centralised water heating systems, making for a more convenient retro-fit.

Industrial Process Heat

Industrial process heat represents a massive opportunity to deploy solar heating.  See earlier blog post: An Untapped Opportunity

With the advent of the Renewable Heat Incentive, the stage is set for heating companies to help their customers cost-effectively reduce fossil fuel use in a wide range of commercial heating applications.

An Untapped Opportunity? - Solar Thermal for Industrial Process Heat

An EU research programme, So-Pro, has identified the enormous opportunity to utilize solar heating in industrial applications.  Many national markets across the EU boast levels of solar thermal deployment in residential buildings that leave the UK far behind (see earlier blog), but when it comes to industrial applications, we’re all absolute beginners.

The UK’s Renewable Heat Incentive is the first scheme of its kind in the world, and could act as a real driver for businesses that use heat in their industrial processes to consider using solar thermal to reduce their dependence on fossil fuel energy, save on bills and get cash-back from the government at the same time.

So-Pro estimates that 30% of total industrial heat demand is at temperatures below 100°C, and may therefore be suitable for solar heating.  The programme highlights a number of case studies where solar energy was successfully deployed in an industrial setting:

·         Food Industry

A producer of dried meat in Jerez de los Caballeros, Spain installed a 250 m² solar thermal array to heat 30,000 litres of hot water storage for washing processes in production, and for cleaning of vessels and machinery. 

·         Metal Processing

An electroplating company in Rahden, Germany installed a 220 m² solar array to support the heating of the galvanising baths to 80°C.

·         Drying

A brewery in Neumarkt, Germany installed a 72m² solar array to preheat air for drying processes in the malt house.

·         Washing

A specialised truck washing company in Villamuriel de Cerrato, Spain installed a solar thermal system of 140m² to heat water for washing tankers used to transport chemicals, food and industrial oils.

·         Preheating Steam Make-up Water

A laundry in Marburg, Germany installed a 57 m² solar system to raise the temperature of make-up water feeding two gas-fired steam boilers.

The successful implementation of these bespoke renewable energy installations were found to require close cooperation between M&E contractors with a detailed understanding of their customers’ heating processes and technically competent solar suppliers or installers that could ensure the design achieved efficient use of the solar technology.

With the advent of the Renewable Heat Incentive, the stage is set for heating companies to help their customers cost-effectively reduce fossil fuel use in a wide range of commercial heating applications. 

To find out whether your application for industrial process heat may be suitable for solar heating, try this checklist of questions

Q: When is a roof not a roof? A: When you put a solar panel on it

The launch of a new roofing standard for solar panels in the UK aims to fix this

Not a roof?

                “Will these solar panels make my roof leak?”
                “Will they blow off the roof in the wind?”
                “Will the fire-safety of the roof be affected?”

You might think that being able to confidently answer “no” to the questions above would be a position that solar manufacturers would aim for, if only for their own peace of mind.  However, with the exception of a small number of companies that have tested their products, the solar industry has avoided the need to comply with important regulations that apply to all other roofing materials for years. 

With the release of new roofing requirements (MCS 012) from the Microgeneration Certification Scheme (MCS), in the UK at least, this ends now. 

Aren’t there existing standards for solar panels?

European standards exist for both solar thermal and solar photovoltaic panels.  While these are excellent tests of the durability of the panels, they do not consider their performance as part of a building.  For example the wind loading test in the European standards for solar panels doesn’t fix the panels to a representative roof – even though the weakest link is often between the fixing brackets and the roof itself.  The weatherproofing tests only check if water gets into the solar panel, not whether it gets into the building.

MCS 012
This new standard published by the MCS now requires that solar roofing installation kits are tested by an independent test laboratory which will issue a certificate declaring the resistance to wind loads and the fire rating.  In addition there will be tests to confirm that the installation doesn’t decrease the weathertightness of the roof.

MCS 012 now requires tests for fire safety, weatherproofing and wind resistance

Installers must calculate the maximum wind load on the roof and check that the strength of the panel and its fixings are adequate.  Depending on the fire rating of the solar panel kit there may be restrictions on where the panels can be placed and the maximum area that can be given over to solar panels.

For a briefing document with more details of the MCS 012 standard, click here.

For a technical note on how the Building Regulations for Fire Safety apply to roof-integrated solar panels, click here.

Do Heat Pumps Deliver?

Do heat pumps actually deliver the energy and carbon savings that housing professionals and energy assessors predict?  A study by the Energy Saving Trust (EST) appears to show that they don't.

The measure of the performance of a heat pump is the coefficient of performance (COP).  This is the ratio of the heat energy that it delivers to the electrical energy that the unit consumes to do so.  An electric fan heater or storage heater would have a coefficient of performance of 1.0 - every unit of electricity consumed in the device ends up as a unit of heat energy in the building.  Heat pumps use electricity more intelligently than this, driving a condensation cycle which cools the ground or air outside a building and delivers the energy as higher temperature heat inside.  The technology is similar to a refrigerator, which transfers heat from inside the fridge to the room outside using the same principle.

For a heat pump to produce a carbon saving relative to a gas-fired boiler in the UK, it needs to be operating at a COP higher than 2.35.  This is because grid electricity has a high carbon-intensity.  When you consume a unit (kWh) of electricity, 0.52kg of carbon dioxide are emitted at a power station.  When you use a gas boiler to produce a unit of heat for your home, around 0.22kg of carbon dioxide are emitted from its flue.

70% of homes would have had lower carbon emissions with a gas boiler

The chart above shows the range of COPs measured in the EST trials (white) compared to the range of COPs claimed by manufacturers (orange) and used to calculate household energy for building regulations.

Fully 70% of households in the EST field trial would have lower carbon emissions from heating their properties if they had instead selected much cheaper gas-boilers.  It also appears that building regulations calculations are over-stating the efficiency of heat pumps by around 60% compared to the real-life examples in the trial.

Can any professionals from heat pump companies offer an explanation for the EST trial results, or highlight errors in this analysis?  Please leave your comments below.  Check workings here if you like.

Note Added 28/03/2012:

Thanks for all the comments to the original post.  The explanation appear to be that  heat pump performance is strongly diminished if it is:

• attached to inappropriately sized heat emitters (for example too small radiators)
• sized wrongly for the heat load
• not used correctly (for example run hard for short periods)

Following on from the EST trial, a group of trade associations created a document to help with the first two issues.  The heat emitter guide helps installers of heat pumps ensure that they achieve more optimal system design and achieve heat pump performance that approaches the laboratory test conditions.